Burner for low pressure lpg torch

ABSTRACT

An improvement in a low pressure torch having a source of gas, a valve, and a gas outlet wherein gas passes through said valve and exits into a torch burner at a pressure between 24 and 28 psig. An improved burner for said torch comprising a generally elongated housing containing a generally straight central bore having a constant diameter over a major portion of its distance, said central bore having an inlet in registry with said gas outlet, an air inlet, and an air-gas outlet forming a burner tip.

O United States Patent 1 1 1111 3,806,038 Nelson Apr. 23, 1974 BURNER FOR LOW PRESSURE LPG 1,961,751 6/1934 Feyling 431/349 TORCH 2,631,659 3/1953 Wright..... 2,888,979 6/1959 Lindgren 431/349 [75] Inventor: John M. Nelson, Rochester, NY.

[73] Assignee: Bernzomatlc Corporation, Primary Examiner-M. Henson Wood, Jr.

Rochester, N.Y. Assistant Examiner-John .1. Love 1 a [22] Filed: June 30, 1972 2312:) Age"! Burgess Dmklage & [21] Appl. No.: 267,823

' [57] ABSTRACT [52] U.S. Cl 239/407, 239/431, 4433110334593, An improvement in a low pressure torch having a 51 I Cl Bosh 7/24 source of gas, a valve, and a gas outlet wherein gas 'ii 430 passesthrough said valve and exits into a torch burner 1 o r 6 at a pressure between 24 and 28 psig. An improved v burner for said torch comprising a generally elongated housing containing a generally straight central bore [56] References Cited having a constant diameter over a major portion of its UNITED STATES PATENTS distance, said central bore having an inlet in registry 3,223,139 12/1965 Smith et a1 431/349 X with said gas outlet, an air inlet, and an air-gas outlet 3,333,775 8/1967 Van De R0812. 239/431 forming a burner tip 3,574,506 4/1971 Locke 431/349 2,683,484 7/1954 Falligant 431/349 9 Claims, 2 Drawing Figures BURNER FOR LOW PRESSURE LPG TORCH BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is directed to providing a burner for a low pressure torch of the LPG type. Specifically, this invention is directed to solving problems in low pressure liquid propane or petroleum gas torches of the portable type. This invention is especially directed to an improved torch for an LPG burner of the low pressure type, which burner provides a parabolic, laminar, attenuated flame at low pressure. The invention is also directed to an inexpensive type burner which can be constructed to fit on existing gas outlets for low pressure LPG gas torches.

2. Discussion of the Prior Art Generally speaking, low pressure LPG gas torches are new. These torches are designed to meter gas to be ignited at a low pressure generally between and 30 psig. The gas is metered to a gas outlet end in the form of a cooking stove, a torch burner, or the like. It has become desirable in connection with these low pressure gas torch burners to provide a suitable burner end which will form the flame into a parabolic, laminar, attentuated flame. While there are many advantages of these low pressure torches, a distinct disadvantage occurs in forming suitable burner flames due to the operating conditions under which the gas exits from the gas outlet associated with valve means disposed between the gas outlet and the gas source.

Generally speaking, the art has taught the use of an integrally formed burner tip wherein the gas is passed through a spud or other gas opening into a Venturi section maintained within the housing of a burner. The Venturi section had an increasing diameter as it moved downstream to the burner exit.

It was found, however, that while these Venturi sections were particularly useful in high pressure LPG gas torches, they were of considerably less value in low pressure operations. The reason for the same was not initially apparent, as it was generally believed that the shape of theseVenturi sections assisted in aspirating air through the air inlet and helped in the intermixture of gas and air as it travelled toward the burner tip. However, such was found not to be the case.

It became desirable, therefore, to provide a suitable burner tip which would permit intermixture of the air readily and which would provide a desirable parabolic, laminar, attenuated flame which could not conveniently be provided using the Venturi section containing burners of the prior art. Such burners are shown, for instance, in U.S. Pat. No. 3,574,506, FIG. 5, assigned to the assignee hereof.

SUMMARY OF THE INVENTION Broadly, this invention contemplates an improvement in a low pressure torch having a source of gas, a valve, and a gas outlet wherein gas passing through said valve and exiting'at said outlet is at a pressure at said outlet of between 24 and 28 psig, the improvement which comprises an improved burner for said torch comprising a generally elongated housing containing a generally straight central bore having a constant diameter over a major portion of its distance, said central bore having an inlet end in registry with said gas outlet, an air inlet and an air-gas outlet.

In a particularly desirable embodiment, the present invention contemplates such an improved burner for a torch wherein the central bore is a circular bore having a diameter of at least 20 times that of the gas outlet, and said central bore is in registry with said gas outlet. It is particularly desirable to provide such a burner wherein the diameter of the central bore is between 36 and 24 times the diameter of the gas outlet and between LS and 1.0 times the diameter of the air inletS.

An important feature of the present invention is the use of an expanded central bore of generally constant diameter. Generally, the diameter is constant for at least percent of its length from the gas outlet to the air-gas outlet constituting the burner tip. It should be understood, however, that minor modifications can be made. Thus, it is possible to have an intermediate zone of varying diameter disposed between two areas of constant diameter, provided that such area of varying diameter constitutes no more than 10 percent of the length of the central bore measured from the gas outlet of the torch to the air-gas outlet of the burner.-

DESCRIPTION OF DRAWINGS A preferred embodiment of the present invention can be seen when reference is made to the accompanying drawings, in which:

FIG. 1 is a sectional elevation of a pressure regulator valve to which is connected a preferred burner assembly, pursuant to the present invention; and

FIG. 2 is an enlarged sectional elevation of the burner shown in FIG. 1.

DESCRIPTION OF SPECIFIC EMBODIMENTS A preferred embodiment of the present invention is shown in the accompanying drawings. The accompanying drawings show a desirable pressure regulator valve more fully disclosed in-co-pending U.S. Pat. No. application Ser.-No. 257,363, filed May-26, 1972 1972, of Milos Chvatal. In accordance therewith, there is provided a gas inlet 2 which is adapted to enter a liquefied petroleum gas cylinder, especially of the portable type. The gas inlet terminates in a narrow defined passageway 4 maintained within a first housing 6. Passageway 4 terminates in chamber 8 in which there is fitted a needle 10 of a needle valve 12 terminating in an outwardly disposed knob member 14. The purpose of the needle valve is to regulate the flow of gas entering gas inlet 2 and passing through chamber 8.

Downstream of chamber 8 is a second chamber 16 in which sits a tire valve 18. The tire valve terminates in a stem 19 which bears against a plate 20.-The plate 20 is the movable member which determines'the extent to which stem member 19 moves inwardly or outwardly to allow passage of the gas in chamber 16 through the tire valve assembly 18. The regulation of the position of stem 19 and thus the flow of gas through the tire valve 18, is, in turn, regulated by the position of the diaphragm 22 which bears against plate 20.

Diaphragm 22 in turn is positioned between the plate 20 and a plate 24 which is spring biased by coil spring 26 maintained within a central bore 28. To facilitate disposition of the diaphragm 22 against plate 20, and thus, a stem 19, in response to ambient conditions, there is provided an air inlet 30in communication with the central bore 28. The purpose of this is to permit the regulation of the gas passing through the regulator valve in response to the ambient conditions of temperature and pressure. The purpose of the gas regulator valve is to permit constant maintenance of a preset or preselected pressure, generally about 26 psi. Thus, by presetting the spring 26 against plate 24 and thus, against the diaphragm 22, a constant resistance is maintained against the needle or stem 19. This changes only in response to changes in ambient conditions facilitated through use of the air inlet 30 in communication with the central bore 28. It should be understood that the air entering air inlet 30 does not mix with the gas. A seal is provided via a suitable washer, such as washer 32. The washer is positioned to allow the diaphragm 22 to be positioned tightly against the internal metallic structure of the housing 34 containing the central bore 28.

As seen in FIG. 1, the gas exit can terminate in an orifice 70 about which is positioned an ring 72. Four air holes 74 are provided on the side of said orifice to allow air to mix with the gas passing through the gas outlet and into the torch assembly positioned therebeneath. The torch assembly comprises a mixing tube 76 in communication with an expansion area 78 which terminates in a flame holder 80. The stippling in the drawing indicates theadmixture of the gases and the relative concentration of flame at the tip of the torch. Specifically, the stippling at 82 and 106 shows portions of intense heat. Flame also exists in the area 84.

Referring once again to the burner shown in detail in FIG. 2, it is to be understood that the burner can be constructed employing a tube of continuous dimension from the burner air inlet at point A to the gas-air outlet at point B, although the embodiment in FIG. 2 shows a minor length of central bore having a varying diameter at 102. The embodiment in FIG. 2 has such minor varying diameter central bore 102 to accommodate methods of construction only. It is important, however, that the length of the bore from point A to point B have a degree of variation in its diameter, such as occurs between points C and D, of less than percent of the total length A-B. There is contemplated within the scope of the present invention a central bore wherein, for instance, a first passageway having a constant diameter abuts a second passageway having a larger but constant diameter. In such case, no variation is considered to have occurred throughout a distance. It is important that the burner be so constructed as to compensate for the marked reduction in the ability of the gas exiting from the gas outlet to pick up air through air inlet 74 en route to the burner tip 104. I-Ieretofore, the Venturi sections are wholly inadequate in low pressure systems due to the diminished ability of the exiting gas to create a negative pressure area downstream of the air holes 74 and thereby pulling atmosphereic air through said holes to maintain a constant supply or flow rate of air-gas mixture at the burner tip. It was found that by expanding the gas inlet and the central bore of the burner, surprisingly, the flame produced was not only extremely hot and characterized by maximum efficiency of gas, but also it could be formed into a desirable parabolic, laminar, attenuated flame. Moreover, it was found that by provision of a suitable exit member, such a flame.

could also be formed into an exteriorly running flame skirt as shown in FIG. 1 by the arcuate shaped outwardly disposed dark stippled portions of flame at 106.

These flames are provided by disposing towards the tip of the burner an outwardly flared tip member 108 defining an outwardly directed annular channel 109. By providing such a concentrated volume of the flame in the form of a skirt, it is possible to use these low pressure LPG flame torches even in high winds and to maintain the flame in the desired parabolic, laminar, attenuated flame shape. The realization of such a flame is considered particularly surprising when one bears in mind that it is generally considered that by decreasing the ratio of the gas outlet to the gas inlet of the burner, better air pick-up for air passing through air inlet 74 can be expected. By expanding such central bore diameter relative to the gas outlet, one would, therefore, have expected less efficiency in the burner. It was further to have been expected that by eliminating the Venturi sections in the burner, one would have provided a flame which did not make maximum use of fuel supplied due to inadequate mixing of the entrained air through the burner. However, it was found that such was not the case. Indeed, flames provided by the instant burner are characterized by the most desirable temperature profiles for the flame produced at the tip thereof. Additionally, such is provided without expensive parts or difficult to construct central bores.

As stated above, a relationship exists between the diameter of the central bore and the air inlet. Generally, the air inlet should have a diameter between 0.7 and 1.3 times that of the gas inlet 112 to the burner. Preferably, this valve is between 0.9 and 1.1. Similarly, the relationship of the gas inlet 112 to the gas outlet is such that the gas inlet 112 has a diameter between 21 and 24 times that of the gas outlet. It has been found that these relationships are important for the maximum and most efficient use of the low pressure exiting 'gas and the realization of the parabolic, laminar, attenuated flame.

A particularly desirable embodiment of the present invention resides in the use of clamps or screw threads 116 adapted to snap on or screw around reciprocally threaded threads on the tip of the pressure regulator valve assembly at 118. Thus, the burner of the present invention is useful in a wide variety of low pressure torches and not merely in the preferred embodiment shown in FIG. 1. If the'gas orifice hole is located'within 0.020 inch of the central axis. This can be done merely by affixing the burner to the end of the valve member at the tube 118 by use of suitable clamps or reciprocally threaded members.

It is apparent from the above that the invention is directed specifically to burners for these aforesaid low pressure torches designed to operate at pressures between 20 and 30 psi, and preferably between 24 and 28 psi.

The gas inlet of the regulator valve is connected to a gaseous fuel supply particularly of the liquefied propane gas type wherein the empty cylinder is disposable. Screw threads are provided over the male connection of the cylinder, and the gas inlet 2 extends into the outlet opening of the cylinder forming a gas seal with, for instance, an O ring positioned in the cylinder outlet. The cylinder, when screwed down tight, effects a perfect gas tight seal with the gasket shown in the gas outlet end of the valve regulator. For that purpose, appropriate sealing is provided generally at sealing 3.

The burner can be constructed of any suitable material. Desirably, it is constructedof durable metal parts, particularly brass, stainless steel, or the like.

The terms and expressions used herein have been used as terms of description and not of limitation, as

there is no intention, in the use of such terms and expressions, of excluding any equivalents, or portion thereof, as various modifications and departures will become apparent to those skilled in the art.

What is claimed is: i

1. Low-pressure torch having a source of gas, pressure regulator valve means, and a gas outlet, said pressure regulator valve means being adapted to deliver gas from said source to said gas outlet at a pressure between 24 and 28 psig, burner means for said torch for producing a parabolic, laminer, attenuated flame from gas at said pressure exiting from said gas outlet, said burner means having a generally elongated housing containing a generally straight central bore having a diameter at least 20 times that of said gas outlet, said central bore having a constant diameter over a major portion of its distance, said central bore having an inlet end in registry with said gas outlet, said burner having an air inlet and an air-gas outlet at the end thereof, the diameter of said central bore being between 1 and 1.5 times the diameter of said air inlet.

2. Low-pressure torch of claim 1 wherein the diameter of said central bore is between 24 and 36 times the diameter of said gas outlet.

3. Low-pressure torch of claim 1 wherein the diameter of said central bore is constant for at least 70 percent of its length from the inlet end to the air-gas outlet of the burner.

4. Low-pressure torch of claim 1 wherein said central bore has an area of varying diameter not greater than 10 percent of its length from the inlet end to the air-gas outlet of the burner.

5. Low-pressure torch of claim 1 wherein said burner comprises a plurality of succeeding central bores each having a constant diameter.

6. Low-pressure torch of claim 1 wherein the diameter of the air inlet of said burner is between 0.7 and 1.3 times the diameter of the inlet end of the burner.

7. Low-pressure torch of claim 1 wherein the inlet end of said burner has a diameter between 21 and 24 times that of said gas outlet.

8. Low-pressure torch of claim 1 wherein said burner has an outwardly flared tip defining an outwardly directed annular channel whereby said flame has an outwardly flared skirt portion.

9. Low-pressure torch of claim 1 wherein said central bore is circular.

* l t I! 

1. Low-pressure torch having a source of gas, pressure regulator valve means, and a gas outlet, said pressure regulator valve means being adapted to deliver gas from said source to said gas outlet at a pressure between 24 and 28 psig, burner means for said torch for producing a parabolic, laminer, attenuated flame from gas at said pressure exiting from said gas outlet, said burner means having a generally elongated housing containing a generally straight central bore having a diameter at least 20 times that of said gas outlet, said central bore having a constant diameter over a major portion of its distance, said central bore having an inlet end in registry with said gas outlet, said burner having an air inlet and an air-gas outlet at the end thereof, the diameter of said central bore being between 1 and 1.5 times the diameter of said air inlet.
 2. Low-pressure torch of claim 1 wherein the diameter of said central bore is between 24 and 36 times the diameter of said gas outlet.
 3. Low-pressure torch of claim 1 wherein the diameter of said central bore is constant for at least 70 percent of its length from the inlet end to the air-gas outlet of the burner.
 4. Low-pressure torch of claim 1 wherein said central bore has an area of varying diameter not greater than 10 percent of its length from the inlet end to the air-gas outlet of the burner.
 5. Low-pressure torch of claim 1 wherein said burner comprises a plurality of succeeding central bores each having a constant diameter.
 6. Low-pressure torch of claim 1 wherein the diameter of the air inlet of said burner is between 0.7 and 1.3 times the diameter of the inlet end of the burner.
 7. Low-pressure torch of claim 1 wherein the inlet end of said burner has a diameter between 21 and 24 times that of said gas outlet.
 8. Low-pressure torch of claim 1 wherein said burner has an outwardly flared tip defining an outwardly directed annular channel whereby said flame has an outwardly flared skirt portion.
 9. Low-pressure torch of claim 1 wherein said central bore is circular. 